Similar to the Triassic Period, the Jurassic followed a marked episode of mass extinction in the marine realm at the end of the Triassic, however. This extinction event affected all groups of larger benthic foraminifera (BouDagher-Fadel, 2008). The total extinction of the Fusulinoidea was significant as it had survived the much greater Permian extinction but were completely and forever wiped out at the end of the Triassic.Smaller forms of the Textulariina, Involutinina and Miliolina suborders surved, however, only the agglutinated textulariines showed any important evolutionary developments during the Jurassic (BouDagher-Fadel, 2008). The Paleozoic forams had aragonitic/calcareous microgranular walls but during the Jurassic, these were replaced by calcareous walls bonded by organic cement. Agglutinated forms developed large, internally complicated tests and many lineages were produced during the Jurassic.

The Jurassic benthic foraminifera have been systematically studied and classified by many researchers. Please refer to Chapter 4 of BouDagher-Fadel (2008), Dr. Marcelle K. BouDagher-Fadel of the University College of London (University College of London - MIRACLE) from which this page is summarized, for a discussion on the many various authors and regions of the world from which Jurassic benthic foraminifera have been described. BouDagher-Fadel (2008) presents a comprehensive revision of the taxonomy of the main genera of the Jurassic larger foraminifera, their evolutionary lineages and phylogenetic relationships, biostratigraphic ages and paleoenvironmental interpretations.

The dominant larger foraminifera of the Jurassic were the agglutinated Textulariina, Involutinina and the Miliolina, which were present but morphologically smaller. While the Lagenina were present, they were small and simple throughout the Jurassic. The figure to the left depicts the development and evolution of the Jurassic suborders (thick lines) and superfamilies (thin lines) of the larger benthic foraminifera.

SUBORDER INVOLUTININA

Test: enrolled second chamber

Wall: aragonitic but commonly recrystallized to give a homogenous microgranular structure; umbilical region with pillar-like stuctures on one or both sides of the test

Geologic range: Early Permian to Late Cretaceous

Superfamily INVOLUTINOIDEA

Test: consisting of a first chamber followed by a planispiral to trochospiral enrolled tubular second chamber

Geologic range: Early Permian to Late Cretaceous

Family Involutinidae

Test: globular proloculus followed by a trochospiral, coiled tubular second chamber. Secondary lamellar thickenings on one or both umbilical regions.

Aperture: at the open end of the tube

Geologic range: Late Triassic to Late Cretaceous

Andersenolina

Test:may be lenticular and conical in shape. The spherical proloculus is followed by a tubular, trochospiral second chamber.The umbilical side is covered by perforated lamellae added with each whorl and surrounded by small rounded margins. A primary aperture is absent.

Geologic range: Middle Jurassic to Early Cretaceous

Septatrocholina (new genus)

Test: conical, consisting of a globular proloculus followed by a trochospirally enrolled divided tubular second chamber with rudimentary septa around a solid core of pillars filling the umbilical area.

Geologic range: Jurassic

Other significant genera include Involutina, Neotrocholina, and Trocholina. The figure below outlines the phylogenetic development of the Involutinoidea through the Jurrassic.

Involutinoidea: phylogenetic development through the Jurassic (after BouDagher-Fadel, 2008)

SUBORDER TEXTULARIINA

Test: made of foreign particles bound by organic cement

Geologic range: Early Cambrian to Holocene

Superfamily VERNEUILINOIDEA

Test: trochospiral early, triserial of biserial, and later uniserial

Wall: non-canaliculate

Geologic range: late Carboniferous to Holocene

Family Verneuilinidae

Test: biserial tests in early stages. Chambers are globular with a terminal aperture

Duotaxis

Test: reassigned from the Tetrataxinae family to the Verneuilinidae family. Has an early triangular stage and lacks a truly valvular tooth

Geologic range: Triassic to Early Jurassic

Superfamily PFENDERINOIDEA

Test: trochospiral throughout, or one that may become uncoiled. Some forms have a siphonal canal, others develop a central composite columella with pillars between apertural plates and septa

Geologic range: Early Jurassic to Cretaceous

Family Pfenderenida

Test: loose trochospiral with siphonal canals that connect successive apertures in primitive forms. Some forms develop a central composite columella composed of thickened innermost septal ends (‘‘septal buttons’’) with or without additional pillars and a spiral canal between the columella and the thickened septa. A subcameral tunnel (simple or multiple) is present in advanced forms. The chamber interior of advanced taxa is subdivided by vertical or horizontal (or both) exoskeletal partitions, resulting in a reticulate subepidermal layer.

Aperture: always cribrate, areal

Geologic range: Early Jurassic to Late Cretaceous

Subfamily Pseudopfenderininae

Test: trochospirally coilded throughout with no subcameral tunnel. middle of test has siphonal canal or is filled with columella made by interseptal pilllars and calcitic infilled material.

Geologic range: Early Jurassic to Late Cretaceous

Siphovalvulina

Test: trochospirally coiled (high or low) in general with three chambers per whorl; the test wall is canaliculate, but rarely visible as such; interior of chambers free; a twisted siphonal canal connects successive apertures; the aperture is unique, interiomarginal, but may become cribrate in the last chambers of advanced forms

Geologic range: Early Jurassic to Early Cretaceous

Pseudopfenderina

Test: high trochospiral with numerous

chambers. The umbilical part of the chamber interior is filled with numerous pillars that are continuous from chamber to chamber

Geologic range: Early Jurassic

Subfamily Palaeopfenderininae

Test: may be uncoiled with various shapes; a simple or multiple spiral subcameral canal may be present and pillars between apertural plates and septa have calcitic filling giving the appearance of a columella.

Aperture: represented by a number of closely set pores on the base of the test

Geologic range: Jurassic

Family Valvulinidae

Test: trochospirally coiled an generally triserial in the early stage

Wall: microgranular and may be alveolar with simple chamber interior

Aperture: interiomarginal with a large valvular tooth. This family shows the first known example of a crosswise-oblique stolon system among the Pfenderinoidea. Stolons appear as a morphological convergence in different groups of lituoloids (valvulinids, orbitolinids, reniform-discoidal lituoloids)

Subfamily Valvulininae

Test: includes forms with a simple or complicated valvular tooth plate

aperture: simple or cribrate

Geologic range: Jurassic to Holocene

Kilianina

Test: conical, where the central zone septa thicken and coalesce into an almost solid mass. In some forms the later half of the test is formed by thin irregular plates intergrown by finer broadly spaced pillars. The early chambers are trochospiral. They coil along a vertical axis and occupy almost half the test, later they become rectilinear, with the outer parts of chamberlets subdivided by numerous pillars.

Geologic range: Jurassic to Holocene

Valvulina

Test: trochospiral throughout, triserial. The valvular

tooth plate is simple or perforated by supplementary apertures. The primary

aperture is a basal slit

Geologic range: Jurassic to Holocene

Subfamily Parurgonininae

Test: eight or more chambers per whorl with a valvular tooth plate complicated by pillars

Aperture: multiple with a crosswise-oblique stolon system

Geologic range: Late Jurassic

Parurgonina

Test: highly conical test with numerous chamberlets, separated by curved septal extensions of the outer wall in a low trochospire.

Septa: break in the umbilical region to form subconical pillars

Geologic range: Jurassic

Neokilianina

Test: The genus typically has 25 chambers per whorls in the adult stage as opposed to the Kilianina, which have 8. also, there is typically more pronounced development of pillars in the central part of the test

Geologic range: Jurassic

Superfamily LITUOLOIDEA

Test: multilocular, rectilinear and uniserial with plani-strepto or trochospiral coiling in early stages. Radial partitions but centrally with our without scattered,separated pillars

Test: highly conical with a large spherical proloculus enclosed in early planispiral and involute coil. Later briefly trochospiral, then uniserial and rectilinear

Chambers: subdivided in the outer part by many short radial vertical partitions forming quadrate chamberlets (one row to each chamber). Central zone filled with irregular scattered separated pillars of all different sizes

Geologic range: Jurassic

Haurania

Test: delicate radial partitions often bifurcating vertically to form a partial tier of peripheral chamberlets.

Geologic range: Jurassic

Socotraina

Test: non-canaliculate, septate, initially coiled

planispirally or in low trochospire. Uniserial chambers, filled with near-vertical, subradial partitions with a sinuous serpentine form. In the central areas of the

chambers the partitions fuse laterally.

Aperture: consists of many small pores between the partiions and is situated subterminally.

Geologic range: Jurassic

Subfamily Amijiellinae

Test: uncoiled or planispirally coiled

Septa: simple or have a complicated microstructure

Interior of the chambers: simple but some genera may develop pillars; walls may have alveoles

uniserial in megalospheric generations. Radial partitions of chambers are srong and thicken towards the central zone (no pillars) Bifurcate vertically to form a few scattered chamberlets

Geologic range: Jurassic

Bostia

Test: dimorphic, with clearly distinct microspheric and megalospheric generations, characterised by a complicated embryonic apparatus and lack of pillars in the central zone.Subepidermal network formed by irregular radial and transverse partitions.

Geologic range: Jurassic

Ijdranella

Test: A hauraniid with a compressed peneropliform

uncoiled stage and an exoskeleton containing long radial pillars superficially united by a coarse network.

Geologic range: Jurassic

Subfamily Choffatellinae

Test: this subfamily possesses hypodermal alveoles and a planispiral test, however the early part may be streptospiral. Lacks continuously developed endoskeletal pillars

involute with long low chambers. It differes from Pseudoclammina as it has a reticulate subepidermal skeleton comprised of an irregular superficial network made of short radial blades perpendicular to the septa

Test: strepto-or planispirally coiled, that has involute initial chambers and later is uncoiled. Adult chambers are cylindrical or flattened, falciform to cyclical, simple, with radial partitions or with pillars.

Wall: microgranular to agglutinates, imperforate or alveolar, simple or with radial partitions, with or without pillars

Aperture: a single slit or numerous pores

Geologic range: Jurassic to Cretaceous

Genera: Mesoendothyra

Subfamily Orbitopsellinae

Test: early planispiral coiled followed by uniserial part in the adult becoming cylindrical. Alveolar microstructure wall. Interior of chambers are divided by vertical radial partitions and pillars in the central zone

Geologic range: Early Jurassic

Cyclorbitopsella

Test: An orbitopsellinine with adult chambers

becoming annular, pillars in the central zone and a cribrate aperture

Geologic range: Early Jurassic

Orbitopsella

Test: orbitopsellinine with a discoidal test, the

first stage being planispiral followed by a flaring, flabelliform stage with 35 to 40 annular chambers. The wall has simple endoskeletal and exoskeletal pillars.

Test: trochospiral, biseral or triserial in early stages but later may be uniserial or biserial

Wall: agglutinated, canaliculate

Geologic range: Early Jurassic to Holocene

Family Chrysalidinidae

Test: high trocospiral, with quinqueserial, quadriserial, triserial or biserial coiling modes, or with certain consecutive pairs of these.

Aperture: central along the axis of coiling. In quadriserial or quinqueserial forms, an umbilicus is present and the aperture is covered with a broad umbilical flap, which may be penetrated by multiple accessory apertures.

Subfamly Paravalvulininae

The subfamily includes all initially quadriserial or quinquesrial forms, becoming quadriserial or quinqueserial in neanic growth and then quinqueserial, quadriserial or triserial in the adult.

Geologic range: Jurassic

Psuedomarssonella

Test:adult tests are quadriserial or quinqueserial, cribrate aperture, umbilicus concave with no internal umbilical pillars. Umbilical apertural flaps of successive whorls are broad and are axially separated by a narrow space

Geologic range: Jurassic

Redmondoides

Test:quadriserial in the adult form. Umbilicus is concave with no internal umbilical pillars. Apertural flaps of successive whorls are well separated

Septa: flattened with narrow umbilicus

Geologic range: Jurassic

Riyadhella

Test:Forms with septa and terminal faces that are highly convex. Genus was reassigned to the Family

Chrysalidinidae rather than to the Family Prolixoplectidae (Loeblich and Tappan, 1988).

Geologic range: Jurassic

Riyadhoides

Test:quadriserial in adult with

flattened septa, or with septa and terminal

face concave. Geologic range: Jurassic

SUBORDER MILIOLINA

Test: coiled commonly with two or more chambers arranged in varying planes about the longitudinal axis, later they may become involute. Advanced forms may have secondary partitions within the chambers.

Geologic range: Late Triassic to Holocene

Family Nautiloculinidae

Test: free, lenticular, planispiral, and involute with secondary thickening in the umbilical region.

Aperture: equatorial

Geologic range: Late Jurassic to Late Cretaceous

Nautiloculina

Presently, Nautiloculina has been placed systematically in the Milioloidea because some of the miliolines (such as Austrotrillina, Quinqueloculina, etc.) display doublelayered walls like Nautiloculina, although the thin dark layer is internal to the thick transparent layer of the wall of the normal miliolines, but it is external to the wall of Nautiloculina. This classification scheme is under debate.